Method oe producing articles of a vttlcamtzable plastic



A. G. EMERY.

METHOD OF PRODUCING ARTJCLES OF A VULCANIZABLE PLASTIC.

' APPLICATION man MAR. 12. 1915.

15193,883. Q Patented Aug. 8,1916.

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'7 $1 4 Mme-x3 ALBERT G. EMERY, OF BROOKLYN, NEW YORK, ASSIGNOR TO RUBBER REGENERATING COMPANY, A CORPORATION OF INDIANA.

Specification of Letters Patent.

Patented Aug. 8, 31916.

Application filed March 12, 1915 Serial No. 13,856.

To all whom it may concern:

Be it known that I, ALBERT G. EMERY, a citizen of the United States, residing at Brooklyn,-county of Kings, State of New York, have invented certain new and useful Improvements in Methods of Producing Articles of a vulcanizable Plastic, of which the following is a full, clear, and exact description.

My invention relates to a method of producing articles of a vulcanizable plastic, and more particularly to improvements in the production of articles by the so-called dipping method.

Heretofore it has been the custom in making articles of rubber or other vulcanizable plastics by the dipping process or method, to submerge or dip a form having the desired configuration in a bath of the plastic brought means of a volatile solvent. After each submersion or dip of the form, it was exposed to the air for a sufficient interval to allow the solvent to evaporate. When the form had been thus dipped and dried a suflicient number of times to insure the accumulation of the plastic material to the desired thickness, the vulcanizable plastic uponthe form, was subjected to avulcanizing treatment.

By my present invention I am enabled to reduce the time required in volatilizing the solvent in the plastic accumulated upon the surface of the form;

This invention. consists primarily in the method of producing articles of a vulcanizable plastic embodying therein the steps of dipping a form in a bath of vulcanizable plastic made fluid or semi-fluid by a volatile solvent, and vdriving said solvent from the plasticmaterial accumulated upon the form by the application of heat thereto from the interior of the forms; and insuch other novel steps as are hereinafter set forth and described, and more particularly pointed out in the claims hereto appended.

In the accompanying drawing I have shown a form adapted for use in practising my improved method.

In practising he method of my invention I employ a form the outer contour of which will give the required shape to'the article which it is desired. to produce.

to a fluid orsemi-fluid state by While the drawing I have shown a glove form my lnvention is not limited in any sense to the production of gloves or to the use of a form like that shown. This form is dipped in a bath of a vulcanizable plastic, made fluid or semi-fluid by means of a volatile solvent. Ordinarily the plastic is a high grade rubber and the solvent used is a volatile hydrocarbon such as naphtha, benzol, or other similar volatile agent. The form with such of the plastic as has adhered to or accumulated upon the surface thereof is then removed from the bath, and. after the usual manipulation to secure the desired distribution of the material thereon the temperature within the mold is raised to a degree where it will rapidly volatilize the solvent in the plastic and thus cause the plastic to quickly dry. Or the form may be continually maintained at the desired temperature, or it may be partially warmed during the dip and its temperature raised subsequent thereto, the essential of the invention being that the heat may be obtained in whole or in part by a direct application of heat to the form instead of subjecting the form with the deposit of the vulcanizable material thereon to a surrounding heated atmosphere. Moreover my invention contemplates a controllable means for heating the form in order that the temperature thereof may be regulated in any desired manner. The form is repeatedly dipped and the plastic accumulated thereon, repeatedly subjected to the action of the desired high temperature from within and through the form until the desired thickness of rubber free of the solvent is secured. I All portions of the forms should be subjected to as nearly the required degree of'heat as is possible, thus insuring uniformity in the action thereof upon all portions of the plastic upon the form to produce an article having the required thickness at various points.

By the above procedure there will be accumulatedoupon the surface of the form, a homogeneous layer of the plastic, free from stratification or other undesirable characteristics.

When plastic of the desired thickness has been accumulated upon the form by succes- .SiVe dippinga alternated with applications of heattothe plastic through the form to .drive the solvent therefrom, the coated form 1s subjected to a vulcanizing medium. The article may be removedfrom the form and v cured or partly cured in any'preferred manner, such as in soapstone or by what is known as the cold cure, or the article may be semi-cured upon the form, the vulcanization being completed after'it has been rethe heat.

In the accompanying drawing, I have shown a glove form having an outer face a of porcelain or other suitable material adapted to accumulate the plastic while permitting it to be readily stripped therefrom after being vulcanized or semi-vulcanized. This form has afilling or lining b of gypsum or other heatconductive dielectric material, supporting a plurality of resistance coils 0 so. disposed as to develop heat in all parts of the form. At 03 and e I have shown the electrical conductors from which current is supplied to the various resistance devices. In this particular design of form shown,

, each finger portion has a tube f of dielectric or insulating material embedded in the filling therefor, the conductor forming the resistance being passed axially through each tube toward the finger end, and then being coiled about the tube, the wire passing from the end of each coil to and through the next tube. A larger coil 9 wound upon a core h of plaster of Paris or other suitable material is connected in series with the other coils and suflices to heat the body portion of the form.

I do not wish to be limited to the particular arrangement of the electrical resistance elements illustrated, since the same may be arranged in other ways by those skilled in the art. The size or gage of the wires may be varied at different points to produce a greater or less heating efiect at such points, so that the thickness of the article formed at such points may be greater or less accord ing to requirements and also so that the dif ferences in radiation of heat at different polnts maybe compensated for according to the shape and surface area of corresponding parts of the form. This variation may also be attained by providing independent leads to the heating elements at different parts of the form so that the same may be controlled separately. The form may also bemade in convenient sections or divisions adapted to permit separate removal of the parts thereof, thus facilitating the removal of the article before curing or after partial curmg.

by varying'the size of resistance wire, the number of convolutions of the coils or by section'al-izing the applications of the electric current, the heat 'may be generated in particular parts of the form according to the relation between the surface area of such r By employing electric currents so localized parts and their respectivevolumes. It has heretofore been a defect in such apparatus when supplied with a fluid heating medium that the parts of the form having small volobjects of similar shapes varies as the cube 90 of their linear dimensions while the surface area varies as the square of such dimensions.

Where a fluid medium has been employed within a form, the small passages in the -ume and relatively large area cooled more smaller or flatter parts of the form have not allowed suflicient passage of the heating fluid to heat such parts to the required degree, while the parts having larger or more nearly cylindrical form have been over heated, thus producing uneven evaporation of the solvent.

In my improved method the necessary amount of heat applied to a particular part of the form is proportioned directly to the relation existing between the surface areas and the respective volumes of the parts of the form, thus obviating the defect mentioned.. I

Having described my invention, what I ters Patent is:

1. The method of producing articles of a vulcanizable plastic which comprises, dip ping a form into a solution of said plastic claim and desire to have protected by Let- 1 in a volatile solvent, supplying localized heat from within said form in varying degrees of intensity according to the relation of the surface area of the parts of theform to their respective volumes, thereby causing equal rates of evaporation from each unit of the entire surface of said form.

2. The method of producing articles of a vulcanizable plastic which comprises, dipping a form into a solution of said plastic in a volatile solvent, generating-heat within said form in varying degrees of intensity according to the relation of the surface area of the parts of the form to their respective volumes, thereby causing equal rates of evaporation from each unit of the entire surface of said form. f

3. The method of producing articles of a vulcanizable plastic which comprises, dipping a form into a solution of said plastic in a volatile solvent, generatin heat within said form in varying degrees 0 intensity by the production of electric currents in varying degrees of conduction according to the relation of the surface area of the parts of said form to their respective volumes, thereby causing equal rates of evaporation from 1e each unit of the entire surface of said form.

Signed at New York, county of New York and State of New York, this 8th day of March, 1915.

ALBERT G. EMERY. Witnesses:

VERONICA BRAUN,. BLANGHE V. MORAN. 

